Natural products carbene catalysis

The aim of this volume is to convince the reader that metal carbene complexes have made their way from organometallic curiosities to valuable - and in part unique - reagents for application in synthesis and catalysis. But it is for sure that this development over 4 decades is not the end of the story there is both a need and considerable potential for functional organometallics such as metal carbon multiple bond species which further offer exciting perspectives in selective synthesis and catalysis as well as in reactions applied to natural products and complex molecules required for chemical architectures and material science. 

Chiral base catalysis is one of the most versatile and broadly applicable types of catalysis. In particular, the potential of tertiary amines to act both as a base and as a nucleophilic catalyst makes chiral tertiary amines like Cinchona alkaloids a privileged catalyst structure in modem synthesis chemistry. In addition, the field of achiral phosphine and carbene catalysis has proven its potential in numerous applications in the past and it is probably only a matter of time until chiral phosphines and carbenes will also be used routinely for other presently demanding natural product total synthesis (Table 7). 

Incorporation of the new catalysis concept and N-heterocyclic carbene catalysis into multicatalytic systems emerged as a new direction to build up a complex scaffold such as those often found in natural products. Liu et al. developed an enantioselective Diels-Alder reaction via trienamine catalysis of indole-2,3-quinodimethane and activated alkenes. More recently, they combined this Diels-Alder process with N-heterocyclic carbene catalysis for the rapid generation of chiral cyclopentanone-fused tetrahydrocarbazoles with diverse substitution [30]. Mechanistically, with the... 

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